I don’t know how the DM that @Itati has been sending out compares to the instructions in this thread but we have just had the weekend. My just having tagged her above will help in the rare event you have been missed.
Just for info …
One of the possible causes of a 33-504 error is indeed an expired security certificate in the hub itself. Unfortunately a number of hubs manufactured before April last year still had a certificate that expired in March this year which meant they needed to be both sold on and installed by then, and that hasn’t happened for a number of users.
The workaround is to prevent the hub setting its internal clock to the correct date so it doesn’t know the certificate has expired.